Pulverizer

ABSTRACT

A pulverizer comprising a cylindrical casing, the inner wall of which is lined with a liner having a plurality of grooves thereon extending substantially parallel to the centerline of the casing, a plurality of rotors rotatable concentrically about said centerline in the casing, said rotors having a number of radially extending blades respectively. The diameter of rotors up to the tip of the blade is slightly less than the inner diameter of the liner. At one end of said rotors there is provided a disc-shape distributor, and at one end of said cylindrical casing there is provided an end cover having in its center an opening for feeding material. Adjacent to this opening there is provided a chamber wherein material supplied is given a prewhirl movement. Material is then transferred through the opening at the center of the end cover to the center of the distributor. The material is thereafter delivered to the outer periphery of the respective rotors.

United States Patent Takashi Yamagishi 9-13 3 Chome Sakuragaoka, Kugenuma, Fujisawa-shi, Kanagawa-ken, Japan [21] Appl. No. 674,524

[22] Filed Oct. 11, 1967 [45] Patented Oct. 5,1971

[72] Inventor [54] PULVERIZER 10 Claims, 3 Drawing Figs.

52 use 241/43, 24l/56,241/255 s11 Int.Cl ..B02c 13/08, B02cl8/22 501 FieldofSearch ..241/39,43,

[56] References Cited UNITED STATES PATENTS 1,513,279 10/1924 Sawford 241/56 X 2,042,042 5/1936 Frisch 241/186 X 2,709,552 5/1955 Lecher ABSTRACT: A pulverizer comprising a cylindrical casing, the

inner wall of which is lined with a liner having a plurality of grooves thereon extending substantially parallel to the centerline of the casing, a plurality of rotors rotatable concentrically about said centerline in the casing, said rotors having a number of radially extending blades respectively. The diameter of rotors up to the tip of the blade is slightly less than the inner diameter of the liner. At one end of said rotors there is provided a disc-shape distributor, and at one end of said cylindrical casing there is provided an end cover having in its center an opening for feeding material. Adjacent to this opening there is provided a chamber wherein material supplied is given a prewhirl movement. Material is then transferred through the opening at the center of the end cover to the center of the distributor. The material is thereafter delivered to the outer periphery of the respective rotors.

PULVERIZER This invention relates to an improved pulverizer suitable for pulverizing synthetic material, foodstuff and chemical products. The pulverizer is also suitable for decomposing asbestos, asbestos product scraps, lumber, leather and other fibrous materials.

The pulverizer of the present invention comprises a cylindrical casing, the inner wall of which is lined with a liner with a number of grooves thereon extending approximately parallel to the centerline of said casing. A shaft is rotatable around said centerline. Attached to the shaft are a plurality of rotors consisting of a disc having at its periphery a number of radially extending blades, the radial extent of the blades being slightly less than the inner diameter of said liner. A plurality of discs having a smaller diameter than the outer diameter of the rotors are fixed to said shaft which is rotated so that the peripheral speed of rotors is in the range of 50-120 m./s. The whirling action caused by the turbulent air produced by said blades, pulverizes the material supplied therein to a very fine particulate material. Further, the volume of air passing through in the casing transfers material from the first rotor to the following rotors until the pulverized material is discharged from the outlet.

In this kind of pulverizer, due to the amount of turbulent air produced by the blades it is inevitable that the temperature of the air is continually raised as it passes the respective rotors. Therefore, in pulverizing synthetic resins which are apt to be softened or decomposed when the temperature exceeds a certain limit, or in blending chemicals or waxeous materials which are sensitive to heat, the number of rotors must be reduced to keep air temperature below a given temperature limit in order to obtain a thoroughly pulverized product. Generally it is necessary to provide a considerable number of rotors.

Also, if the volume of air passing through the casing is increased, the temperature rise at each rotor may decrease. However the velocity of the air passing in an axial direction in the casing becomes remarkably high. When material is then supplied to an inlet provided on the peripheral surface of casing, the distribution of material at the outer periphery of the first rotor becomes quite uneven. On the other hand, if the number of rotors are reduced the pulverizing efficiency is decreased. Also, if the peripheral velocity of the rotors is increased, the degree of fineness f the pulverized material will not be proportional thereto despite a remarkable increase in motive power for driving the pulverizer. However, this becomes ineffective since there is a limitation on the peripheral velocity which the rotors can attain. Hence, a remarkable temperature rise occurs in each rotor.

The purpose of the present invention is to furnish an improved pulverizer useful for pulverizing synthetic resins or chemicals sensitive to heat while overcoming the abovedescribed prior art problems.

Other objects and advantages of the present invention will be made clear from the following with reference to the accompanying drawings.

FIG. 1 is a vertical longitudinal sectional view of a pulverizer of the present invention.

FIG. 2 is a section view taken along line A--A of FIG. 1.

FIG. 3 is a secton view, with parts broken away, taken along lines B-B ofFlG. 1.

In the drawings, 1 represents cylindrical casing, the inner peripheral surface of which is covered with a liner 3 provided with a plurality of grooves 2 thereon extending substantially parallel to the axis of the casing.

At the opposite ends of the casing there are provided end covers 4 and 5 respectively. Attached to respective covers are bearing cases 6 and 7 which have journaled therein a shaft 8.

At one end of the shaft 8 there is provided a pulley 9 a belt 10 thereon whereby said shaft is rotated with a high speed about the center line of the casing in a direction shown by an arrow in drawings. Mounted to the shaft 8 are: a disc 11 having a plurality of blades 12 thereon, thus forming a distributor 13; a rotor 16, consisting of a disc 14 with plurality of blades 15 fixed at its peripheral portion and extending in a radial direction; a thin flat plate disc 17; a rotor 20 consisting of a plate disc 18 with a plurality of blades 19; a disc 21; a rotor 24 consisting of a disc 22 with a plurality of blades 23; a disc 25; a sleeve 26 for the shaft 8; an impeller 29 with a plurality of blades 28 extending in a radial direction; and a collar 30. The discs 21 and 25 are identical with disc 16 except for their locations. At the center of the end cover 4, there is provided a path 4 for feeding material. Also a cylindrical or annular-shaped chamber 31 communicates with air and material feeding inlet 32 through a path 33 extending in a tangential direction for said chamber 31.

The part of easing 1 surrounding the outer periphery of impeller 29 forms an annular chamber 34, one end of which communicates with outlet 35. The casing l is divided into upper and lower casings 36, 37 respectively and as seen in FIG. 3, both are held together with bolts 38. As seen from FIG. 2, the end cover 4 consists of upper part 39 and lower part 40 and both are secured by bolts 41. By removing bolts 38, 41 and further removing bolts 42 connecting the upper casing 36 to end cover 5, then by pulling handle 43 provided on the upper casing 36 in a direction shown by arrow A43, the upper casing 36 and upper part 39 of end cover 4 can be pivoted about pin 43', engaged to the leg of lower casing 37.

When the shaft 8 rotates at high speed, the distributor 13 and impeller 29 function to introduce a large volume of air through the inlet 32. Such air passes through the path 33 into chamber 31 where it is whirled about shaft 8 in the same direction as the rotation of shaft 8 and is sucked into the center of distributor 13. Then air discharged from the outer periphery of the distributor 13 passes through the outer peripheries of rotors 16, 20 and 24 respectively and into the center of impeller 29. The air is thereafter discharged from the periphery of impeller 26 to the annular chamber 34 in casing I and escapes from the outlet 35.

Material to be pulverized is continuously fed by means of a supplier to inlet 32 and delivered in floating status with the airstream flowing through path 33 into chamber 3l wherein the air is whirled at a high speed. The material is given a highspeed whirling movement in the center of chamber 31, and thereby is sucked into distributor 13. The material is then discharged from the periphery of the distributor 13 in uniform distribution in respect to every portion of the periphery thereof and supplied to the chamber partitioned by blades 15 of rotor 16 wherein it is pulverized by striking the ends of rotating blades 15 and/or by impinging on the liner 3. Such pulverization is mainly effected by impinging or frictional contact of the granular materials against one another in the highspeed whirl produced by the blade 15 and/or by pressurized turbulent vibrations. Then material is blown through the path between the liner 3 and the periphery of disc 17 into the space around the periphery of rotor 20 where it is subjected to pulverizing action again and further delivered to the space around the periphery of rotor 24 to be pulverized as before.

The material thus pulverized is passed by impeller 29 with the air through the whirl-shaped chamber 34 into a pipe connected to the outlet 35 and can be delivered to a cyclone separator or the like for separation into the pulverized material and air.

According to the present invention, material is mixed beforehand with air necessary for effecting pulverization in the path 33 and cylindrical or whirl-shaped chamber 31 where it is given a prewhirl movement. Then such material is blown in uniform distribution along the whole peripheral face of the end cover adjacent the chamber 31 into distributor 13 wherein it is gradually accelerated and further delivered in uniform density around the periphery of rotor 16. The material is trapped in the turbulence produced by the blades 15 in the chamber partitioned by said blades 15. In this chamber, the material is completely pulverized and then transferred to rotor 20 so that the density of the material at the peripheries of rotors 20 and 24 is kept uniform at all times. In this manner, the entire periphery of each rotor is effectively utilized.

1n the conventional apparatus, a material inlet is provided at the side of easing 1 and material is supplied therefrom to one point of the periphery of the first rotor 16. Some of the material is trapped in the chamber partitioned by blade 15, and, without being subjected to complete pulverization action, the material is passed to the next rotor 20. Such material is further passed under like conditions to the next rotor 24. Due to these circumstances there will be a considerable amount of roughly crushed or half-crushed material mingled with the pulverized material.

Assuming that the inner diameter ofliner 2 is 400 m./m., the outer diameter of rotors 16, and 24 are 394 m./m., the width of blades 15, 19 and 23 are 100 m./m., and the outer diameter of discs 17, 21 and are 375 m./m. In this device, when polyethylene pellets are pulverized with rotor speeds of about 500 rpm. and with air volumes of about 20 m./min. the peripheral velocity of rotors 16, 20 and 24 will be about 10.3 m./s., the annular area between discs 17, 21, 25 and the inner diameter of liner 2 will be approximately 0.016 m.*. The velocity of the air stream in an axial direction through said space will be approximately 21 m./s. Accordingly, the ratio of the velocity of travelling material in a peripheral direction to the velocity of that in an axial direction to be 10.3/25 or about 0.41. The length of rotor 16 in an axial direction, i.e., the distance from one point at its center to a near end of the next rotor 20 is about 50 m./m. The length of the outer periphery of the rotor will be about 1,230 m./m. and the ratio of this length to the axial length of the rotor will be 1,230/50 or about 25. it will be therefore understood that under such condition, the material is apt to be short passed.

According to the present invention, this disadvantage is eliminated. lf pulverization of material is made with the apparatus of the present invention to obtain the same fineness of material as is done by the conventional apparatus, the former may achieve it with a fewer number of rotors then that of the latter, yet there will not be any rough-crushed material.

Under the pulverizing conditions as set forth above, approximately 10 C. temperature rise is produced for each rotor. Obviously it is more advantageous to employ the apparatus with a fewer number of rotors. 1n the apparatus of the invention the temperature rise of the pulverized material such as synthetic resin, is limited to 50-80 C.

Also fewer rotors results in less weight and size of the apparatus. Stated otherwise, if as many rotors are provided in the apparatus as those in the conventional apparatus, the volume of air can be increased. in this manner there will not be any short-passed material. Thus, heat produced by pulverization is absorbed in the air which in turn results in the reduction of the temperature of the product.

As has been done in the conventional apparatus, if material is forced around the periphery of the first rotor 16 by means of a screw feeder provided at the outside of the casing, the material tends to be torn and crushed at the periphery of the rotor 16. In this manner, a thermoplastic synthetic resin will easily melt, a thermosetting synthetic resin will be hardened.

Even with the supply of air with the material to the periphery of the first rotor, heat and turbulent noise are nevertheless produced. Hence there is an unnecessary impulsive loss against the air which loss is considerably large.

According to the present invention, the large volume of air supplied into the apparatus has been given a prewhirl movement in the chamber 31 and then delivered to the center of distributor 13 whose peripheral speed is comparatively low, whereby any impulse loss is small. Further, when the air is accelerated up to the peripheral speed of the rotor 16 in said distributor, the loss is small. Therefore there is no excessive temperature rise and power loss.

lnstead of providing chamber 31, if the path 33 is made to turn at its lower portion to be open directly at the inner diameter of the blade 12 of distributor 13, material tends to be struck at the inner end of the blade 12. That material which is irregularly struck is blown out of the apparatus. This is particularly so when the material is cylindrical or spherical pellets of resilient synthetic resin. However according to the present invention, when the material is supplied in floating status in air to the center of distributor 13, the material struck at the inner end of blade 12 will be minimized. If any of the material is impinged irregularly by the blow of blade 12, it will be trapped within the chamber 31 and again sucked to distributor 13 with the mixture of air and material whirling in said chamber. In this manner, there will be no material that is blown out of the apparatus.

In putting the apparatus of the present invention to the actual practice, there is brought forth an advantage incidental thereto as follows. For supplying a mixture of pulverized material and air to the cyclone or the like, the whirl-shaped chamber 34 around the periphery of impeller 29 should be so designed as seen in drawings that said mixture of pulverized material and air is to be discharged vertically upward. According to the present invention, the inlet 32, path 33 and cylindrical or whirl-shaped chamber 31 are provided with the end cover 4, none of which are on the cylindrical surface of casing 1. Due to this factor, casing 1 may be divided into an upper casing 36 and lower casing 37 at 45 angle relative to the horizontal along the centerline of shaft 8 by simply disengaging bolts 38, 41 and 42 without removing the material supplying device and pipe connected to the outlet 35. in this manner, the half of the rotatable elements may be exposed by pivoting the upper casing 36 and upper half 38 of end cover 4 about pin 43'.

This is very convenient for inspecting and cleaning the interior of the apparatus for effecting complete preventive maintenance. This is particularly so when one is to see if material deposits in the interior of the apparatus or to clean the same with a pneumatic pressure airstream for removing deposits when various colored materials are treated therein. Further, when the lower casing 37 supports end cover 5 in the plane at 45 angle relative to the horizon, the tension of belt 10 is securely supported.

lclaim:

1. ln a pulverizer comprising a cylindrical casing, the inner surface of which is covered with a liner having a plurality of grooves thereon, a shaft journaled in said casing, rotors having a plurality of radially extending blades and rotatable about said shaft, a disc-shaped distributor provided adjacent one end of said rotors, said distributor having blades thereon, a discshaped impeller provided at the opposite end thereof, and an end cover attached at one end of said casing having in its center a material-feeding inlet, said inlet opening into said distributor at said shaft, and another end cover attached to the opposite end of said casing, the improvement wherein said cylindrical casing includes an outlet, said grooves extend substantially parallel to the centerline of said casing, said shaft is rotatable about said centerline, a plurality of flat discs are attached to said shaft, each of said rotors has a diameter up to the tip of said blades which is slightly shorter than the inner diameter of said liner, said rotors and said flat discs are arranged alternately in contact relation to one another, said impeller has radially extending blades, said rotors are rotated at a high speed so that their peripheral speed is in the range of 50-120 m./s. whereby material is pulverized mainly by air tur' bulence produced by said rotor blades and said material is discharged with a volume of air from the outlet by the action of said impeller, an annular chamber is provided connected to said material feeding inlet so that all of the material and air necessary for performing pulverization of material are fed to said chamber and first given a whirling movement in a direction of the rotation of said shaft, and said distributor is attached to said shaft on the upstream side of said rotors, whereby material and air is supplied to the outer periphery f said radially extending rotor blades.

2. In a pulverizer comprising a cylindrical casing, the inner surface of which is covered with a liner having a plurality of grooves thereon, a shaft journaled in said casing, rotors having a plurality of radially extending blades and rotatable about said shaft, a disc-shap distributor provided adjacent one end of said rotors, said distributor having blades thereon, a discshaped impeller provided at the opposite end thereof, and an end cover attached at one end of said casing having in its center material-feeding inlet, said inlet opening into said distributor at said shaft, and another end cover attached to the opposite end of said casing the improvement comprising a whirl chamber provided adjacent the material feeding inlet formed in the center of said end cover at said one end of said casing wherein material supplied from sad inlet is given a prewhirl movement before reaching said distributor.

3. A pulverizer comprising:

a cylindrical casing having an inlet port and an outlet port;

a liner covering the inner surface of said casing;

a shaft rotatable in said casing;

a plurality of rotors mounted on said shaft for rotation therewith and arranged in series between the inlet and outlet ends; each rotor having radially extending blades, the outer extremities thereof terminating short of said liner;

a disc-shaped distributor adjacent said inlet end and having blades thereon fixed on said shaft;

a whirl chamber between said inlet port and said distributor;

a disc-shaped impeller adjacent said outlet opening said impeller being fixed to said shaft and having radially extending blades thereon;

said inlet port, whirl chamber, distributor, rotors, impeller and outlet port being arranged for causing air and material which is to be pulverized and which is fed into said inlet port to be given a prewhirling movement in said whirling chamber in the direction of rotation of said shaft and then to be supplied by said distributor to the outer periphery of said radially extending rotor blades where the material is pulverized and from whence said pulverized material is carried to said outlet port.

4. The device of claim 3 in which an annular opening about said shaft is provided between said whirl chamber and distributor whereby the air and material is fed to the inner portions of said distributor, and said distributor is constructed to force said air and material radially outwardly to the space between said extremities of said rotor and the liner of said cas- 5. A pulverizer according to claim 3 characterized in that a plurality of axially spaced flat discs are attached to said shaft between said rotors, thereby fonning a plurality of partitioned areas in said casing.

6. A pulverizer according to claim 3 characterized in that an end cover is provided adjacent the material feeding inlet and said whirl chamber is formed in the center of said end cover wherein material supplied from said inlet is given a prewhirl movement.

7. A pulverizer according to claim 1, wherein the said blades of said distributor extend radially and axially of the axis of rotation of said shaft.

8. A pulverizer according to claim 3, wherein said casing is divided into an upper casing and lower casing separable for permitting access to said rotors.

9. The pulverizer according to claim 15 in which the abutting surfaces of said upper and lower casing come together in a plane at an angle to the horizontal, and means on said lower casing for pivoting said upper casing about said lower casing.

10. A pulverizer according to claim 9, wherein said angle is approximately 45. 

1. In a pulverizer comprising a cylindrical casing, the inner surface of which is covered with a liner having a plurality of grooves thereon, a shaft journaled in said casing, rotors having a plurality of radially extending blades and rotatable about said shaft, a disc-shaped distributor provided adjacent one end of said rotors, said distributor having blades thereon, a discshaped impeller provided at the opposite end thereof, and an end cover attached at one end of said casing having in its center a material-feeding inlet, said inlet opening into said distributor at said shaft, and another end cover attached to the opposite end of said casing, the improvement wherein said cylindrical casing includes an outlet, said grooves extend substantially parallel to the centerline of said casing, said shaft is rotatable about said centerline, a plurality of flat discs are attached to said shaft, each of said rotors has a diameter up to the tip of said blades which is slightly shorter than the inner diameter of said liner, said rotors and said flat discs are arranged alternately in contact relation to one another, said impeller has radially extending blades, said rotors are rotated at a high speed so that their peripheral speed is in the range of 50-120 m./s. whereby material is pulverized mainly by air turbulence produced by said rotor blades and said material is discharged with a volume of air from the outlet by the action of said impeller, an annular chamber is provided connected to said material feeding inlet so that all of the material and air necessary for performing pulverization of material are fed to said chamber and first given a whirling movement in a direction of the rotation of said shaft, and said distributor is attached to said shaft on the upstream side of said rotors, whereby material and air is supplied to the outer periphery f said radially extending rotor blades.
 2. In a pulverizer comprising a cylindrical casing, the inner surface of which is covered with a liner having a plurality of grooves thereon, a shaft journaled in said casing, rotors having a plurality of radially extending blades and rotatable about said shaft, a disc-shaped distributor provided adjacent one end of said rotors, said distributor having blades thereon, a disc-shaped impeller provided at the opposite end thereof, and an end cover attached at one end of said casing having in its center material-feeding inlet, said inlet opening into said distributor at said shaft, and another end cover attached to the opposite end of said casing the improvement comprising a whirl chamber provided adjacent the material feeding inlet formed in the center of said end cover at said one end of said casing wherein material supplied from sad inlet is given a prewhirl movement before reaching said distributor.
 3. A pulverizer comprising: a cylindrical casing having an inlet port and an outlet port; a liner covering the inner surface of said casing; a shaft rotatable in said casing; a plurality of rotors mounted on said shaft for rotation therewith and arranged in series between the inlet and outlet ends; each rotor having radially extending blades, the outer extremities thereof terminating short of said liner; a disc-shaped distributor adjacent said inlet end and having blades thereon fixed on said shaft; a whirl chamber bEtween said inlet port and said distributor; a disc-shaped impeller adjacent said outlet opening said impeller being fixed to said shaft and having radially extending blades thereon; said inlet port, whirl chamber, distributor, rotors, impeller and outlet port being arranged for causing air and material which is to be pulverized and which is fed into said inlet port to be given a prewhirling movement in said whirling chamber in the direction of rotation of said shaft and then to be supplied by said distributor to the outer periphery of said radially extending rotor blades where the material is pulverized and from whence said pulverized material is carried to said outlet port.
 4. The device of claim 3 in which an annular opening about said shaft is provided between said whirl chamber and distributor whereby the air and material is fed to the inner portions of said distributor, and said distributor is constructed to force said air and material radially outwardly to the space between said extremities of said rotor and the liner of said casing.
 5. A pulverizer according to claim 3 characterized in that a plurality of axially spaced flat discs are attached to said shaft between said rotors, thereby forming a plurality of partitioned areas in said casing.
 6. A pulverizer according to claim 3 characterized in that an end cover is provided adjacent the material feeding inlet and said whirl chamber is formed in the center of said end cover wherein material supplied from said inlet is given a prewhirl movement.
 7. A pulverizer according to claim 1, wherein the said blades of said distributor extend radially and axially of the axis of rotation of said shaft.
 8. A pulverizer according to claim 3, wherein said casing is divided into an upper casing and lower casing separable for permitting access to said rotors.
 9. The pulverizer according to claim 15 in which the abutting surfaces of said upper and lower casing come together in a plane at an angle to the horizontal, and means on said lower casing for pivoting said upper casing about said lower casing.
 10. A pulverizer according to claim 9, wherein said angle is approximately 45*. 